The Samsung TVs in 2013 established a special sensor with a name Eco Sensor.
On the ecology of this sensor is irrelevant. His only purpose of automatically adjust screen brightness depending on the lighting in the room.
When enabled, the eco sensor, putting the brightness to the level of 40, with the bright light of the room, such as the day, the sensor detects the amount of light will automatically set the brightness of the screen 90. This has its drawbacks, and by increasing the brightness a bit worse contrast. The manufacturer has taken into account that not all users like and be comfortable to watch TV with automatic brightness control, the sensor can be switched on or off, the menu option is available.
The benefits of energy savings, but considering the power consumption of modern TVs, a possible saving of 0.001%. Reducing the impact on the eyes, less fatigue and irritation of the eyes from intense brightness of the screen.